THE REDOX BEHAVIOR OF FERROCENE DERIVATIVES .1. 1,2,3-TRITELLURA[3]FERROCENOPHANE AND 1,3-DITELLURA[3]FERROCENOPHANES

The electrochemical behaviour of 1,2,3-tritellura[3]ferrocenophane, [Fe(C5H4Te)2Te), and 1,3-ditellura[3]ferrocenophanes, [Fe(C5H4Te)2E'] (E'= S, Se, or CH2), has been examined and compared to that of the known tri- and di-chalcogena[3]ferrocenophanes. All the complexes undergo a chemically reversible one-electron oxidation. 1,2,3-Tritellura[3]ferrocenophane also exhibits a clean reduction step, even if complicated by subsequent chemical reactions. Discrete variational (DV-Xalpha) calculations relative to the model compounds [Fe(C5H4Te)2Te], [Fe(C5H4Se)2Se], and [Fe(C5H4S)2S] allow an unambiguous assignment of the molecular orbitals involved in the oxidation and reduction processes. They suggest that the all-tellura[3]ferrocenophane complex, [Fe(C5H4Te)2Te], is the most accessible both to one-electron addition and removal steps.